Support and defend the Constitution of theUnited States against all enemiesProtect the United States, its possessions, andareas vital to its interestsAdvance the policies and interests of the UnitedStatesSafeguard the internal security of the UnitedStatesThe DoD is headed by the SECDEF, who isappointed to the Presidents cabinet and the NationalCabinet Security Counsel.Secretary of DefenseThe National Security Act Amendments of 1949redesignated the National Military Establishment asthe Department of Defense and established it as anexecutive department with the SECDEF as its head.Since that time, many legislative and administrativechanges have occurred, evolving the department intothe structure under which it currently operates.Under the President, the SECDEF, by virtue of anexecutive order, has responsibility for all thePresidents functions involving the DoD. Thosefunctions include the Presidents powers, duties, andauthorities. As the Presidents principal assistant inDoD matters, the SECDEF reports to the President onall DoD military matters. SECDEF authority includesthe separately organized military departments of theArmy, Navy, and Air Force; the Joint Chiefs of Staff;the unified combatant commands; and various defenseagencies established for specific purposes. TheSECDEF is the principal defense policy adviser to thePresident. SECDEF is responsible for the formulationof general defense policy and policy related to DoD,for the execution of approved policy, and for exercisingdirection, authority, and control over the DoD.Under the SECDEF, each military department (theDepartment of the Navy [DoN] includes naval aviationand the United States Marine Corps) is separatelyorganized under its own secretary and functions underthe authority, direction, and control of the SECDEF.The secretary of each military department isresponsible to the SECDEF for the operation andefficiency of his or her respective department. Ordersto the military departments are issued by the SECDEFthrough the secretaries of these departments, or theirdesignees, under authority specifically delegated inwriting by the SECDEF, or provided by law. Thecommanders of the unified combatant commands areresponsible to the President and the SECDEF foraccomplishing the military missions assigned to themand exercising command authority over forcesassigned to them. The operational chain of commandruns from the President to the SECDEF to thecommanders of the unified combatant commands. TheChairman of the Joint Chiefs of Staff functions withinthe chain of command by transmitting the orders of thePresident or the SECDEF to the commanders of theunified combatant commands.Joint Chiefs of StaffThe Joint Chiefs of Staff consist of the Chairman;the Vice Chairman; the Chief of Staff, U. S. Army; theChief of Naval Operations; the Chief of Staff, U.S. AirForce; and the Commandant of the Marine Corps.Supported, subject to the authority of the chairman, bythe Joint Staff, they constitute the immediate militarystaff of the SECDEF. The chairman is the principalmilitary adviser to the President, the National SecurityCouncil, and the SECDEF. The chairman is appointedby the President with approval from Congress. Theother members of the Joint Chiefs of Staff are militaryadvisers who may provide additional information uponrequest from the President, the National SecurityCouncil, or the SECDEF. They also may submit theiradvice when it does not agree with that of theChairman. The vice chairman of the joint chiefs acts aschairman in the absence of the chairman. Subject to theauthority of the President and the SECDEF, thechairman is responsible for the following:Assisting the President and the SECDEF inproviding for the strategic direction andplanning of the armed forcesAllocating resources to fulfill strategic plansComparing the capabilities of American andallied armed forces with those of potentialadversariesPreparing and reviewing contingency plans thatconform to policy guidance from the Presidentand the SECDEFPreparing joint logistic and mobility plans tosupport contingency plansRecommending assignment of logistic andmobility responsibilities to the armed forces tofulfill logistic and mobility plansThe chairman advises the SECDEF on criticaldeficiencies and strengths in force capabilities5-3